GEOCHEMICAL JOURNAL
Online ISSN : 1880-5973
Print ISSN : 0016-7002
ISSN-L : 0016-7002
Volume 2, Issue 3-4
Displaying 1-5 of 5 articles from this issue
  • Akimasa Masuda
    1968 Volume 2 Issue 3-4 Pages 111-135
    Published: 1968
    Released on J-STAGE: April 08, 2008
    JOURNAL FREE ACCESS
    Lanthanide concentrations in 13 fractions of the Norton County achondrite have been determined by a mass spectrometric isotope dilution method. A most remarkable fact is that the distribution of lanthanides is quite different between enstatite single crystal and polycrystalline material. This difference is interpreted in terms of different formation processes. It is thought that in the growth of single crystals, individual ions were placed one by one to build a strictly defined lattice structure, whereas the polycrystalline material was produced by the transitional formation of amorphous phases or phases of low crystallinity resulting from spontaneous cohesion of neighboring ions in the melt. The lanthanide patterns for single crystal fractions are grossly similar to each other, but there is some variation between them in fine structure of the patterns. This can be interpreted as a reflection of the fact that the partition of lanthanides into single enstatite crystals is more or less sensitive to rather subtle differences in the conditions of crystal growth. The genesis of Shalka, Johnstown (both hypersthene achondrites) and eucritic achondrites can be interpreted in terms of the precipitation of single crystals only. A great difference in partition coefficient between single crystals and polycrystalline material system appeares to be of much petrological significance, because it is thought that the difference can also bring about a great difference in efficiency of enrichment of calcium in remnant liquid. Irregular behavior of Cc, Eu, and Yb in a few single-crystal fractions was ascertained by independently processed redeterminations. The irregularities may be ascribed to single crystals favoring higher valence state of these elements relative to the melt. It is suggested that lanthanum might have been a little depleted relative to the other lanthanides in the initial melt that produced Norton County.
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  • Masahiro Yamamoto, Nagashi Ogushi, Hitoshi Sakai
    1968 Volume 2 Issue 3-4 Pages 137-156
    Published: 1968
    Released on J-STAGE: April 08, 2008
    JOURNAL FREE ACCESS
    The Yanahara pyritic ore deposits, Okayama-Ken, was investigated for the distribution of the sulfur isotopes, cobalt, selenium and nickel. The Co/Fe ratio in sulfides, mostly pyrites, varies in the range (0.02-34.7) × 10-4 and the Se/S ratio in the range (0.32-38.4) × 10-5, respectively, while δ34S values with respect to the meteoritic sulfur are almost uniformly distributed around the average, +2.8‰. Cobalt in the Kabu ore body, one of the biggest in the deposits, is distributed in a well defined zonal structure, the Co/Fe ratio decreasing from the south-eastern margin (Gari-Ko) toward the western side of the ore body. Despite of the significant intra-ore body fractionation of cobalt and selenium, the weighted averages of the Co/Fe and Se/S ratios in the Yanahara deposits are very similar to those in the crust, while the Ni/Fe ratio in the ore deposits is much smaller than that in the crust. These features in the isotopic and trace element chemistry of the deposits are shown to be compatible with those theoretically expected on the basis of fractional crystallization of an ore magma. An ore magma may have been separated from a later differentiate of the Yanahara intrusives. When pyrrhotite coexists with pyrite, cobalt seems to be enriched in pyrite, whereas the opposite trend is apparent for selenium. However, the enrichment seems to occur only at the contact of the two minerals, and short range chemical exchange or rearrangement of the trace elements around the boundary is suspected during and/or after the formation of pyrrhotite.
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  • Shizuo Tsunogai, Koichi Ikeuchi
    1968 Volume 2 Issue 3-4 Pages 157-166
    Published: 1968
    Released on J-STAGE: April 08, 2008
    JOURNAL FREE ACCESS
    Ammonia in the atmosphere has been measured in order to study the source of atmospheric ammonia and the circulation of ammonia through the atmosphere and the hydrosphere. Concentration of the atmospheric ammonia over the ocean is 0.2 μg-at/m3 STP. On the other hand, over land ammonia is concentrated, which is 1.25 μg-at/m3 in August and 5.0 μg-at/m3 in February. In calm night, ammonia in the air near land surface increases with time. Thus, atmospheric ammonia is supposed to be supplied mainly from the land surface. Ammonia of anthropogenic origin is predominant in surface air over land in winter. The residence time of ammonia in the atmosphere is estimated to be about 30 days, and is rather short among most of atmospheric gases. The residence time is still too long for most of the atmospheric ammonia to be regarded as being supplied by evaporation from the ocean. In the ocean, the sink of nitrogen compounds must be the biological denitrification, which, as the result, may raise nitrogen content of aerobic sea water by only 0.03 ml/l.
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  • Hideki Matsuda, Kinuko Horie, Masatake Honda
    1968 Volume 2 Issue 3-4 Pages 167-174
    Published: 1968
    Released on J-STAGE: April 08, 2008
    JOURNAL FREE ACCESS
    Activities of two cosmic ray produced radionuclides, 11Be and 26Al, were determined for the Norton County achondrite. 11Be, 22Na, 26Al, 44Ti, 53Mn and 60Co were determined for the Peace River chondrite. Except for 10Be and 53Mn, these activities were measured employing a low level β-γ coincidence method. Combining these data with those reported for stable rare gases, the radiation age of Norton County was calculated to be (120±20) × 106 y which is significantly lower than previous estimations by a factor ranging from 2 to 5. The results for Peace River were compared with other experiments which appeared in literature, and the shielding effect was discussed.
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  • Ryoshi Ishiwatari
    1968 Volume 2 Issue 3-4 Pages 175-184
    Published: 1968
    Released on J-STAGE: April 08, 2008
    JOURNAL FREE ACCESS
    Humic acid from a lake sediment was divided into five fractions by extraction with chloroform (Fr. 1), methyl ethyl ketone (Fr. 2), methanol (Fr. 3) dimethyl formamide (Fr. 4) and extraction residue (Fr. 5). The amount of each fraction is 2, 3, 7, 21 and 67 per cent, respectively. Each fraction was characterized by elementary composition, IR and NMR spectra. From Fr. 1 to Fr. 5, methylene, methyl and carboxyl bonds decrease, and ketone or quinone groups increase. Proteinous and carbohydrate-like organic substances are present in Frs. 3, 4 and 5. There is a linear relationship between color intensity of the fractions and their H/C ratio. These results suggest that the humic acid is composed of many intermediates of "humification" of plankton bodies. No direct evidence could be obtained for the presence of aromatic hydrogen in the fractions.
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